N-乙酰半胱氨酸对大气细颗粒物致大鼠肺损伤的拮抗作用

Effects of N-acetylcysteine on pulmonary oxidative and inflammatory lesions induced by surrounding fine particulates(PM2.5) in rats

目的探讨N-乙酰半胱氨酸(NAC)对大气细颗粒物(PM2.5)急性暴露致大鼠肺炎性损伤及氧化应激损伤的拮抗作用。方法 48只雄性Wistar大鼠随机分为6组,分别为2个对照组:空白对照组及滴水对照组,4个实验组:PM2.5染毒组及低、中、高剂量NAC干预组。空白对照组不给予任何干预措施,滴水对照组给予气管滴注灭菌注射用水(1 ml/kg)1次/周,共4次,PM2.5染毒组大鼠给予气管滴注7.5 mg/kg的PM2.5悬液1次/周,共4次,低、中、高剂量NAC干预组分别给予125、250、500 mg/kg NAC灌胃6 d,第7天气管滴注7.5 mg/kg的PM2.5悬液,重复此过程3次。所有大鼠于4周后处死。苏木精-伊红染色观察大鼠肺组织病理变化。酶联免疫吸附试验检测大鼠血清中C反应蛋白(CRP)、肿瘤坏死因子-α(TNF-α),支气管肺泡灌洗液(BALF)中TNF-α,肺组织匀浆的TNF-α、白细胞介素1β(IL-1β)。标准比色法测定血清及BALF中的乳酸脱氢酶(LDH)、丙二醛(MDA)。结果肺组织病理切片光镜下观察PM2.5染毒导致大鼠肺组织破坏,随着NAC干预剂量增加肺组织破坏程度减轻,两个对照组大鼠肺组织病理未见明显异常。PM2.5组、低、中、高剂量NAC干预组的血清CRP及TNF-α水平、BALF中的TNF-α水平、肺组织中的TNF-α及IL-1β水平均高于两个对照组(均P<0.05),给予NAC干预后血清CRP及TNF-α水平、BALF中的TNF-α水平,肺组织匀浆中的TNF-α及IL-1β水平低于PM2.5组(均P<0.05);PM2.5组、低、中、高剂量NAC干预组血清及BALF中的LDH活力、MDA水平均高于两个对照组(均P<0.05),给予NAC干预后血清及BALF中的LDH活力、MDA水平低于PM2.5组(均P<0.05)。结论 NAC可拮抗PM2.5导致的大鼠肺炎性损伤和氧化应激损伤。

Objective To evaluate the effects of N-acetylcysteine(NAC) on lung tissue of Wistar rats, which were tracheally instilled fine particulate matter(PM2.5). Methods Forty-eight male Wistar rats were randomly divided into six groups: two control groups [they were blank group(C1), fake treatment group(C2) separately], four treatment groups(they were PM2.5 group(P), low-dose NAC group(L), medium-dose NAC group(M), high-dose NAC group(H)separately)C1 received no treatments at all. C2 was instilled with sterile water(1 ml/kg) tracheally once a week for four times. P was instilled equivoluminal PM2.5 suspension(7.5 mg/kg) tracheally once a week for four times. The NAC groups received gavage(10 ml/kg) of different dosage of NAC(125, 250, 500 mg/kg) for six days. At the seventh day, the NAC groups were instilled PM2.5 suspension(7.5 mg/kg) tracheally. The procedures were repeated for three times in the NAC groups. Twenty-four hours later after four weeks or after the last instilling, all rats were sacrificed. Lung tissue was stained by hematoxylin-eosin(HE) staining, and histopathological changes of lung tissue were observed by optical microscope. The levels of C-reactive protein(CRP) as well as tumor necrosis factor-α(TNF-α) of serum, TNF-α of bronchoalveolar lavage fluid(BALF), TNF-α as well as interleukin-1β(IL-1β) of homogenates of lung tissue were detected by enzyme-linked immunosorbent assay. The activity of lactate dehydrogenase(LDH) as well as the levels of malondialhyde(MDA) of serum and BALF were detected by standard colorimetric method. Results HE staining showed that the normal structure of lung were destroyed in the groups dealed with PM2.5 and NAC could alleviate these changes.Higher dosage of NAC seemed to provide more powerful protections. Structure of the lung in C1 as well as C2 were nearly normal. The levels of CRP as well as TNF-α of serum, TNF-α of BALF, TNF-α as well as IL-1β of homogenates of lung tissue in the groups of P, L, M, H were higher than that in the groups of C1, C2(all P<0.05). The levels of CRP as well as TNF-α of serum, TNF-α of BALF, TNF-α as well as IL-1β of homogenates of lung tissue in the groups of L, M, H which groups received NAC treatments were lower than that in P group. More, the groups seemed to have lower levels of CRP,TNF-α, IL-1β when higher dosage of NAC were given. The activity of LDH as well as the levels of MDA of serum, and BALF in the groups of P, L, M, H were higher than that in the groups of C1, C2(all P<0.05). The activity of LDH as well as the levels of MDA of serum and BALF in the groups of L, M, H which groups received NAC treatments were lower than that in P group(all P<0.05). Conlusion To some extent, NAC demonstrate antagonistic effects on oxidative stress and inflammatory injury on rats’ lung brought by PM2.5.